US2524552A

US2524552A - Hydraulic actuator for turbine stop valves

Info

Publication number: US2524552A
Application number: US710366A
Authority: US
Inventors: Lawrence B Wales; Frank C Linn
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1946-11-16
Filing date: 1946-11-16
Publication date: 1950-10-03
Anticipated expiration: 1967-10-03

Description

Oct. 3, 1950 HYDRAULIC Filed Nov. 16, 1945 L. B. WALES ETAL ACTUATOR FOR TURBINE STOP VALVES 2 Sheets-Sheet 1 Figl Oct. 3, 1950 WALES ETAL 2,524,552

HYDRAULIC ACTUATOR FOR TURBINE STOP VALVES Filed Nov. 16, 1946 2 Sheets-Sheet 2 Fig.2,

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' *GBZH 74 I 667/ 52 75 3 M 69 79a '1 63 70 53 5s Inventors:

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Patented Oct. 3, 195% HYDRAULIC ACTUATOR FOR TURBINE STOP VALVES Lawrence B. Wales, Marblehead, Mass., and Frank C. Linn, Schenectady, N. Y., assignors to General Electric Company, a corporation of New York Application November 16, 1946, Serial N 0. 710,366

6 Claims.

1 This invention relates to valve actuating mechanisms, more particularly to a hydraulic motor actuator for quick-acting stop or shut-off valves such as those for controlling the flow of a fluid operating medium to a prime mover, for instance a steam turbine.

In steam turbine powerplants it is usual to have a stop' valve arranged to quickly shut off the flow of operating medium to the turbine, the valve being controlled by the emergency overspeed governor of the turbine. Such valves are ordinarily arranged to have a wide open and a fully closed position, and are positioned by a suitable motor, preferably a positive displacement hydraulic motor.

Heretofore, it has been customary in hydraulic motors for valves of this type to provide two liquid supply conduits and one discharge conduit. One supply conduit furnished the fluid necessary to actuate a relay valve, and a separate supply conduit furnished the fiuid for actuating the hydraulic motorv to position the valve. By contrast, a valve actuating mechanism in accordance with this invention requires only one supply conduit which furnishes liquid to both a relay valve and the hydraulic motor in series, thus eliminating one fluid supply conduit.

An object of the invention is to provide an improved actuating mechanism for a quick-acting, shut-oil valve.

Another object is to provide an improved hydraulic motor having a novel relay valve arrangement for controlling the motor.

A fufther object is to provide an improved hydraulic actuating mechanism of the type described having a simplified piping arrangement.

Other objects and advantages will be apparent from the followin description taken in connection with the accompanying drawings, in which Fig. 1 is a schematic drawing of a prime mover powerplant having a quick-acting shut-off valve embodying the invention; and Fig. 2 is a sectional view of the valve and

motor assembly

5, 6, l of Fig. 1.

Referring now to Fig. 1, it will be seen that a prime mover such as a steam turbine 3 is supplied with fluid operating medium through a conduit 4 containing a shut-off valve 5 actuated by a hydraulic motor 6 under the control of a relay valve 1. A liquid supply pump l0 draws liquid from a reservoir ll through a conduit i2 containing check valve 8| and is driven by suitable gearing 9 from the shaft 8 of the prime mover.

mover is necessary for supplying hydraulic pressure when the prime mover is at rest. This may conveniently be in the form of a liquid supply pump lfla driven by electric motor 9a and in parallel with the prime mover driven pump It, as shown in Fig. 1. Pump Illa is arranged in conduit l 2a; containing check valve 8i a.

A valve i9 is provided in the pump discharge conduit an and comprises a housing it having an inlet port l5, an outlet port it, and a drain conduit Hi. The valve stem it is biased downwardly by coil spring I 9 and carries a pair of axially spaced discs 20 and M arranged to cooperate with

seats

20a and 2! a, respectively. During normal operation of the powerplant, stem It is engaged by a spring biased latch 32, thus seating disc 2i to shut oii communication with drain conduit ill and unseating disc 20 so that inlet port it is in communication with outlet port 5.. Latch 22 is arranged to be tripped by an emergency governor 23 which is carried on shaft 8 of the prime mover 3. Liquid under pressure from supply pump l0 passes through control valve 13 to the relay valve 1 through conduit 80. Spent operating liquid is discharged from the relay valve 1 to reservoir ii through a conduit 19. Preferably the low pressure drain conduit 19 is arranged to enclose the high pressure supply conduit 80, in a manner and for purposes well known to those skilled in this art.

The sectional view of Fig. 2 shows details of the relay valve 1 and valve 5, in the closed position. Shut-off valve 5 comprises a housing 24 provided with a port 25 opening into an inlet chamber 26. A ring member 21 forms a valve seat and is secured in housing 24 by suitable means, as by welding at 21a. A discharge chamber 28 communicates with an outlet port 29. For improving the aerodynamic performance, a shield in the form of a hollow cylinder 30 is secured to the removable head 3|. This shield arrangement is not a part of the present invention but is disclosed more completely in the copending It will be understood by those familiar with this art that pump means independent of the prime application of G. B. Warren and E. E. Parker, Serial No. 592,322, filed May '7, 1945, and assigned to the same assignee as the present application and now Patent No. 2,483,163, issued September 27, 1949. The valve disc assembly 32 is arranged to seat against ring member 21 and is carried on the. ireeend of a valve stem 33 which is slidably disposed, in a support and sealing bushing assembly-34. The valve stem 33 is adapted for connection by a coupling sleeve 35 to a piston rod 36 of motor 6.

to which is secured a cylinder head 38 by suitable the piston 42. Suitable piston rings 46 are provided to reduce leakage around piston 42 to a minimum. Any leakage past the piston which does occur will be drained through a port 41 in the housing 31, thence through drain conduit 48 into the discharge chamber 48 of relay valve 1. Piston rod 36 is slidably arranged in a packing gland 58 and is connected to .piston 42 by means of a head 5| which engages the inner surface of a recess in the under side of piston 42. A threaded plug 52 is screwed into the recess to retain head The relay valve 1 has an outer housing 53 with an end plate 54 secured to e, flange 55 by suitable threaded fastenings 56. A threaded drain plug 51 may be provided in plate 54. Formed integral with motor housing 31 is the relay valve cylinder 58 having an inlet port 59 into which liquid supply conduit 80 is threaded. Secured to the cylinder 58 by threaded fastenings 6| is a head 62 carrying a piston stop member in the form of a hollow cylinder 83 with one or more ports 64 arranged to permit liquid to enter and fill the bore 63a of the stop cylinder. A plunger 65 is slidably arranged in cylinder 58 and is biased downwardly by a coil spring 66 so as to rest on the end of stop member 63, as will be apparent from the drawing. Plunger 65 fits loosely around the stop 63. A restricted orifice 61, the purpose of which will appear hereinafter, is provided in the upper end of plunger 65. Formed in housing 31 above the plunger 65 is a port 68 which admits operating liquid from relay valve 1 to motor 6. A cylindrical liner 69 may be secured in cylinder 58, by pressing, shrinking or other method, to provide a smooth sliding surface for the plunger 65. A piston ring 18 is arranged to keep fiuid leakage around the plunger 65 to a minimum. in cylinder 58 so that any leakage past piston 65 can return to the discharge chamber 48. Ports 1| have the additional important function of providing a large area passage for draining fluid from beneath the motor piston 42, thus permitting the shut-off valve disc 32 to descend rapidly, under the influence of biasing spring 43 when the supply of operating liquid to the motor 6 is discontinued.

Manual control means may be provided in the form of lever 12, arranged so that the valve actuating mechanism can be tested without disturbing the emergency governor 23 or control valve l3 of Fig. 1. Lever 12 is pivoted to the coupling sleeve 35 and is fulcrumed on a rod 13 by means of a yoke 18. Rod 13 is slidably arranged in a bore in housing 31 and is of suflicient length so as to extend across conduit 14 and into a port which is arranged to communicate between conduit 14 and chamber 49. A bushing 16 threaded into housing 31 at the upper end of rod 13 serves to minimize leakage around rod 13 and also provides a stop when raising or lowering lever 12. Upward movement of rod 13 is limited by engagement of shoulder 11 with bushing 16,

One or several ports 1| are provided while downward movement is limited by engage-- ment of yoke 18 with the top surface of'thc bushing.

The operation of our improved tuator is as follows:

A flanged conduit 18a communicates with the drain chamber 48 of relay valve 1, and is connected to the drain conduit 18'. Liquid from sup-' ply conduit 88 enters the relay valve inlet chamber 68, from whence it flows through ports 64 filling the interior of stop member 63 and then passes through orifice 61. Because of the pressure diflferential thus created across the restricted orifice 61, a net upward force will be exerted on the plunger 65. The liquid also fills inlet chamber 68 exerting a pressure on the bottom end of plunger 85. As a result of these hydraulic forces on it, plunger 65 moves upwardly against the bias of spring 86, causing the beveled upper end of the plunger to seat against the valve seat formed by the beveled edge of port 68. In so doing, the discharge ports 1| are sealed oflf from the liquid flow and all fluid passing through orifice 61 will pass through port 68 and build up a pressure on the underside of the motor piston 42, causing it to move upwardly against the action of spring 43, thereby unseating the valve disc assembly 32. Motive fiuid is thus permitted to flow through conduit 4 to the prime mover 3. During normal operation, liquid pressure is maintained on motor piston 42, so that valve disc 32 is held open. The plunger 65 is held in raised position with the top end portion thereof sealing off port 68 as long as liquid pressure is applied to the lower surface of the piston formed by th lower end portion of the plunger, by reason of the fact that the effective area of the lower end surface of the plunger is greater than that of the upper end surface exposed to the fluid pressure within port 68, as will be apparent in Fig. 2.

It may be noted that since the fiow of motive liquid to motor 6 is limited by orifice 61, the rate of rise of valve disc 32 from the fully closed to the wide open position may be preselected by suitably proportioning the orifice.

Assuming now that an overspeed condition occurs in the prime mover 3, the emergency governor 23 will trip latch 22 permitting spring l9 to move spindle |8 downwardly, causing valve disc 28 to seat and disc 2| to unseat. Thus the liquid supply to conduit 88 is shut off and communication between conduit 88 and drain conduit I1 is established. This releases the fiuid pressure from the underside of relay valve plunger 65. The action of spring 66 combined with the pressure of the liquid communicated to the upper surface of plunger 65 through port 68, causes the plunger 65 to move downwardly until it rests on the end of the stop 63. In so doing, the liquid pressure is released from beneath the hydraulic motor piston 42. The liquid will pass through the port 68, around the outside of plunger 65, and through the drain ports 1| into the chamber 49, whence it leaves through outlet conduit 19a and returns to the reservoir through conduit 18. Because of the generous proportions of the

ports

68, 1|, 18a, and the related passages, the

hydraulic acliquid is quickly drained from the motor 6 and the valve disc 32 is rapidly lowered to seat on member 21, thus shutting oil? the flow of operating medium to the prime mover.

For testing purposes, the valve may be tripped manually by raising the lever 12. The liquid below piston 42 will then pass through conduit it, and port thus quickly seating the valve disc 32 and shutto the discharge chamber 49, thence to reservoir H through conduit '19.

ting off the supply of operating medium to the v prime mover.

By arranging the relay valve in series with the hydraulic motor, as described, only a single hydraulic supply conduit is required.

Thus, the invention provides an improved hydraulic valve actuating mechanism, arranged to be simple and reliable mechanically, and requiring a minimum amount of piping.

While a particular embodiment of the invention has been illustrated and described, it will be obvious to those familiar with they art that various changes and modifications may be made without departing -from the invention; and it is intendedtdcover in the appended claims all such changes and modifications as come within the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United states, is:

1. In a hydraulic motor, the combination of a motor cylinder with a piston member slldably disposed therein, a relay valve cylinder having oneend closed and the other end secured to the motor cylinder and having a plunger member slidably disposed therein, conduit means for supplying operating liquid to the closed end of the relay cylinder, walls defining a first port communicating between the relay cylinder and the motor cylinder, springmeans biasing said piston to an extreme position nearest the first port, walls defining a second drain port through the relay cylinder wall adjacentthe first port, said plunger having a first end portion adapted to close the first port and block communication between the first and second ports when in one extreme position, the other end portion of the plunger forming a piston of greater efiective area than that of said first end portion, said plunger having a restricted passage extending entirely therethrough and adapted to communicate liquid from the supply conduit to the first port when in said extreme position,-and spring means biasing the plunger toward the closed end of the relay cylinder so as to uncover the first port and provide direct communication with the second port, whereby liquid is drained from the motor cylinder through the first and second ports when the supply thereof is discontinued, the pressure drop across said restricted passage serving to move the plunger to said extreme position when pressure liquid is-supplied to the closed end of the relay cylinder.

2. In a hydraulic motor, the combination of a motor cylinder having a piston slidably disposed therein, means biasing the piston to one extreme position in its range of movement, said cylinder having a first port adapted to supply liquid to the cylinder for moving the piston toward the other extreme of its range of movement, and a relay valve cylinder connected to the'motor cylinder with one end in communication with the first port, said relay cylinder having a drain port opening through the wall thereof adjacent the first port, a plunger slidably disposed in the relay cylinder and having a first end portion adapted to close the first port to interrupt communication between the first port and the drain port when in a first extreme position, said first plunger and plunger portion I passage extending axially having a restricted through the plunger and adapted to communicate between the first port and the relay valve cylinder when in said first extreme position, the other end portion of the plunger forming a second than that of the first plunger end portion, spring means biasing the plunger away from said first position to the opposite extreme position in which the first port is in free communication with the drain port, and means for supplying liquid under pressure to the relay cylinder only at the side of the plunger remote from the first port whereby the pressure drop in the liquid passing through said restricted passage to the motor cylinder causes the plunger to move to said first extreme posit on and the static pressure of the liquid acting on said second piston serves to hold the plunger in said first extreme position as long as the liquid supply pressure is maintained.

3. In a hydraulic motor, the combination of a, motor cylinder with a piston member disposed therein, means biasing the piston toward one extreme position in its range of movement, said cylinder having a wall portion defining a combined liquid supply and drain port for admitting liquid to cause the piston to move toward the other extreme position in its range of movement, a relay valve for controlling the flow of liquid through said first port and including a relay cylinder having a closed end and an open end communicating with said port and a second drain port opening through the wall of the relay cylinder adjacent the first port and communicating with the exterior of the relay cylinder, and a plunger member slidably arranged in the relay cylinder and having a first end portion adapted to cover the first port to interrupt communication thereof with the second port when in a first extreme position, said plunger having a restricted axially extending passage opening through both ends thereof, the second end portion of the plunger having a second piston with an efiective area larger than that of the first plunger end portion, spring means biasing the plunger toward the closed end of the relay cylinder to establish communication between said first and second ports, and means for supplying liquid under pressure to the closed end of the relay cylinder only whereby the pressure drop across the restricted passage causes the plunger to move to said first extreme position when liquid flows through said passage and the first port to the motor cylinder and the supply pressure acting on said second piston holds the plunger in said first position as long as the pressure is maintained.

4. In a, hydraulic motor, the combination of a housing defining a chamber with an inlet port, a first movable member disposed in the chamber and adapted to be actuated to an extreme position by pressure fluid admitted to the chamber through said port, means biasing the movable member to an opposite extreme position, conduit means for supplying operating fluid to the inlet port, and relay valve means interposed between said conduit and port, the relay valve including a casing having a closed end communicating with the supply conduit at the other end in communication with the inlet port and a drain port adjacent the inlet port, and a second movable member disposed in the casing and having piston having an effective area larger- 7 a first end portion adapted to coverthe inlet port to interrupt communication between the inlet port and the drain port when in a first extreme position, the second movable member having a second end .portion defining a second piston of an eflective area larger than said first end portion, spring means biasing the second movable member toward the closed end of the casing, the second movable member having a restricted passage extending axially through both ends thereof and adapted to establish communication between the supply conduit and the inlet port when-in said first extreme position, whereby said second member is caused to move to its first extreme position under the influence of the pressure differential created across the restricted passage when liquid is supplied therethrough to'the motor chamber and the supply pressure acting on said second piston holds the second member in said first position as long as the supply pressure is maintained.

5. In a hydraulic motor, the combination of a motor cylinder having an operating liquid port in one end thereof and a slidably disposed piston communication with said port, the relay cylinder having a drain port through the wall thereof adjacent said first port, a plunger member slidably disposed in the relay cylinder and having a first end portion adapted to close the first port to interrupt communication between the first port and the drain port when in a first extreme position, the plunger having a second end portion with a second piston of an efiective area larger than that of said first end portion, spring means biasing the plunger away from said first position toward the closed end of the relay cylinder, said plunger defining a restricted passage adapted to communicate between the first port and the chamber defined by said second piston and the closed end of the relay cylinder, liquid supply conduit means connected to the lastmentioned chamber, a casing secured to the motor cylinder surrounding the relay cylinder and spaced therefrom to define a drain chamber communicating with said drain port, and drain conduit means communicating with said drain chamber.

6. In a hydraulic motor, the combination of a motor cylinder having an operating'liquid port in one end thereof and a, slidably disposed piston therein, means biasing the piston toward said port, and a relay valve assembly for controlling the supply of operating liquid to the port including a relay valve cylinder secured to the motor cylinder and having a, closed end remote from'the motor cylinder and an open end in communication with the port, said relay cylinder having a drain port through the wall thereof adjacent said first port, a, plunger member slidably disposed in the relay cylinder and having a first end portion adapted to interrupt communication between the first port and the drain port when in a first extreme position, spring means biasing the plunger away. from said first position toward the closed end of the relay cylinder, the other end portion of the plunger forming a second piston of an eflective area larger than that of said first plunger end portion, said plunger defining a restricted passage adapted to communicate between the first port and the chamber defined by said second piston and the closed end of the relay cylinder, liquid supply conduit means connected to the last-mentioned chamber, a casing secured to the motor cylinder surrounding the relay cylinder and spaced therefrom to define a drain chamber communicating with said drain port, drain conduit means communicating with said drain chamber, walls defining a passage in parallel with said first port and adapted to bypass liquid from the motor cylinder to said drain chamber, valve means in said bypass, and means for actuating said bypass valve to reduce the liquid pressure in the motor cylinder whereby the piston is caused to move towards said first port.

LAWRENCE B. WALES. FRANK C. LINN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,080,706 MacKie Dec. 9, 1913 1,652,360 Jackson Dec. 13, 1927 2,225,518 Blasig Dec. 17, 1940 2,252,418 Shelley Aug. 12, 1941 2,292,095 Thumim Aug. 4, 1942 Certificate of Correction Patent-No. 2,524,552

Octoher 3, 1950 LAWRENCE B. WALES ET AL.

It is hereby certified that error appears in the rinted specification of the above numbered patent-requiring correction as fo ows: Column 6, line 1, for the word and read and; line 72, for at read and;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Ofiice. Signed and sealed this 27th'day of February, A.-D. 1951.

THOMAS MURPHY, Am'qtant 00mm of PM.